The Electron Microscopy Core Facility (EMCF) is a research resource laboratory providing specimen preparation, microscopy, photography and digital imaging services to investigators from both clinical and basic science laboratories within the Mayo Clinic Foundation. The facility is fully equipped to offer standard transmission (TEM) and scanning (SEM) electron microscopy. The facility also performs X-ray probe microanalysis and immuno-gold labeling procedures. Costs associated with this core are recovered primarily through recharges with modest institutional support. The EMCF is requesting support specifically for the development of new techniques and procedures in electron microscopy for Cancer Center Members. In addition, methods in electron tomography, cryomicroscopy, and novel methods for identification and localization at the ultrastructural level are being incorporated into the available services of the EMCF. Incorporation of these methodologies will enable Cancer Center members to study three-dimensional structural features of cells and molecules at a resolution and preservation that were previously unattainable.